Conventionally, various materials such as metals, glass, wood and plastics have been used as a base material in industrial applications, etc. Also, there have been provided various adhesives for bonding these base materials to other materials. In addition, in order to impart various properties such as a rust-proof property, an impact resistance, a water resistance and a weather resistance to these base materials, there have been provided various paints, resin films and coating agents, etc.
However, polyolefin-based plastic materials such as, for example, typically polypropylene, have such a problem that the materials tend to be deteriorated by themselves in bonding property and coatability owing to non-polarity and crystallizability thereof, although they are excellent in properties required as the base material. Therefore, these base materials are generally subjected to bonding and coating only after being previously subjected to surface treatments such as chemical treatment, corona discharge treatment and flame treatment. However, the effects of these surface treatments tend to be hardly stabilized owing to adverse influence by shapes of the base materials. In addition, the surface treatments tend to require use of special facilities, resulting in complicated process.
In addition to the above surface treatments, there is also known a method of directly modifying the base materials themselves to improve their bonding property and coatability by previously subjecting these materials to chlorination, grafting, etc. However, this method has such a drawback that it is not effective to improve a bonding property, a coatability, etc., of the existing base materials. In consequence, at present, any suitable method which is capable of effectively improving a bonding property or a coatability of the base materials without subjecting the materials to pretreatments, has not still been established.
On the other hand, as special adhesive materials, there have been proposed a resin composition comprising a specific polyolefin obtained by oxidative degradation (Patent Document 1) and a block copolymer obtained by bonding an isotactic polypropylene having a (mmmm) pentad content of 10 to 60% based on whole pentads therein to a polar group-containing polyolefin (Patent Document 2). However, these adhesive materials are very expensive.
Patent Document 1: Japanese Patent Application Laid-Open (KOKAI) No. 6-192617
Patent Document 2: Japanese Patent Application Laid-Open (KOKAI) No. 2005-48172